Crystals formed in the molten rock of a volcano may help predict the next eruption of Mount St. Helens or Mount Vesuvius as far as a year in advance, researchers said.
Drawing from data of the explosions of Mount St. Helens in 1980 through 1986 in Washington, scientists found that iron- and magnesium-rich crystals grew before an eruption, according to a study in the journal Science. The most rapid growth happened in the 12 months before the volcano exploded, the analysis showed.
Volcanos often erupt with little clear warning, and efforts to predict them rely on monitoring seismic activity, ground deformations, gas emissions and changes in water levels and chemistry, according to the U.S. Geological Survey. The latest finding may help scientists better gauge the signs and give advance warning of a potentially fatal eruption.
“Volcanoes tend to erupt in a similar cycle and have similar trends,” said Kate Saunders, a study author and geologist at the University of Bristol in England, in a telephone interview. “If we can work out their behavior, it allows us to know what to look for. We can better evaluate the monitoring signals.”
Saunders said that she and her colleagues “have no predictions on what might erupt soon.”
Volcanoes have killed 29,000 people worldwide since 1980, according to the U.S. Geological Service. There are about 169 active volcanoes in the U.S., mostly in Alaska, and about 1,500 worldwide.
Mount St. Helens
Mount St. Helens exploded on May 18, 1980, after months of earthquakes and smaller explosions. The eruption killed 57, including David Johnston, the geologist who first radioed word of the eruption from an observation post nearby. Johnston’s insistence that the public be barred access to the area that year saved thousands of lives, according to the USGS.
About 12 months before the eruption, iron and magnesium-rich crystals grew more quickly, and data show the growth of these crystals took place at the same time as increased earthquake activity and gas emissions, according to the paper. That may mean that new magma pulsed into the volcano’s inner chamber, and may provide scientists with a view into the hidden life of a volcano.
Of the active U.S. volcanoes, 54 are considered a high or very high threat to public safety, according to the USGS. Besides the danger to people on the ground, a volcano explosion can threaten air travel, as when KLM Flight 867 with 240 passengers aboard encountered an ash cloud from the 1989 eruption of Mt. Redoubt near Anchorage, Alaska, causing the engines of the plane to fail. Though the crew landed the plane safely, $80 million in damage was done to aircraft.
Saunders said her future research will focus on linking crystal composition to other monitoring techniques, enabling for even better understanding of volcanoes. The crystals are like a book that provides scientists with a record of what’s happening within the volcano, she said.
“If you know your alphabet, you can read the book,” Saunders said. “And the better we understand a volcano, the better we can predict eruptions.”